JPS58110617A - Metal heat treatment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a metal heat treatment method.

Heat treatments of metals, such as annealing, spheroidizing, sintering, placing, malleable, and hardening, are usually preferably carried out in a reducing or non-oxidizing atmosphere in a furnace. Heat treatment can be performed in patches or continuously. Continuous heat treatment furnaces are usually open ended.

These furnaces include an inlet for the metal or workpiece to be heat treated, a heat treatment zone, a cooling zone, and a workpiece outlet. The workpiece is passed through the furnace at a certain speed, heated in a heat treatment zone to the desired treatment temperature, and then cooled in a cooling zone to a temperature at which it will not oxidize when exposed to ambient air. The required atmosphere is usually created, for example, by an exothermic or endothermic gas generator or an ammonia cracker.

The atmosphere is supplied to the heat treatment zone and expands to fill the gas space within the furnace. Since the atmosphere is particularly flammable, combustion must normally occur at both the inlet and the outlet of the furnace. There are therefore two directions of flow inside the furnace, and gas emanates from the heat treatment area in both directions.

The gas must be supplied at a flow rate sufficient to maintain a positive pressure within the furnace. Otherwise, there is a risk that air will flow into the furnace from the inlet or outlet of the furnace, creating a hot oxidation condition inside the furnace. It is therefore practical to feed at a flow rate in excess of what is theoretically necessary to create the required reducing or non-oxidizing conditions within the heat treatment zone.

It is an object of the present invention to provide a heat treatment method that improves the drawbacks of such conventionally practiced methods.

According to the invention, a method for heat treating metal in a continuous furnace comprising a sequentially provided inlet, heat treatment zone, cooling zone and outlet, wherein air enters the furnace through the inlet and the outlet. introducing non-reacting gases and reducing gases at predetermined locations within the furnace, subjecting substantially the entire furnace to non-oxidizing or reducing conditions, and, if necessary, controlling the heat treatment area. A method is provided comprising the steps of creating a gas flow within the furnace to create an atmosphere of different composition in the furnace and the cooling zone, and passing cough metal through the furnace from the inlet to the outlet.

The term "non-reactive gas" as used herein refers to a gas that does not react with other components of the atmosphere and with the workpiece or metal being heat treated. Nitrogen is generally used as the non-reactive gas, but in some cases, argon may be used if nitrogen has any deleterious effect on the metal being heat treated.

Furthermore, the term "heat treatment of metals" as used herein includes annealing (including spheroidization), sintering (for example, of powders including non-metallic powders), solaging, hardening, and malleable. The method of the invention is particularly suitable for annealing and sintering.

The method of the invention is suitable both for horizontal continuous furnaces (furnaces in which the workpiece is fed entirely horizontally) and for vertical furnaces (furnaces in which the workpiece is fed in a vertical direction).

Examples of horizontal continuous furnaces include continuous strip wire furnaces,
There are Metschwerd furnaces, low two-bed furnaces, and Zoscher furnaces.

Typically, non-reacting gases and reducing gases are introduced directly into the heat treatment zone of the horizontal furnace. Alternatively, the gases are directed to one or more cooling zones near the heat treatment zone;
Alternatively, it may be introduced at a location further away from the heat treatment zone, or both, where a substantial portion of the reducing gas is pressurized to flow into the heat treatment zone. Normally, non-reacting gases and reducing gases are introduced into the furnace at ambient temperature, but since the heat treatment zone can reach temperatures as high as 1100°C (gK) depending on the type of heat treatment being carried out, a substantial amount of the gas in the heat treatment zone is Expansion occurs. The gas is therefore forced to flow from the heat treatment zone both in the direction of the furnace inlet and in the direction of the cooling zone.

In the case of a horizontal furnace, it is preferred that the amount of gas exiting the heat treatment zone is substantially greater at one end of the zone than at the other end. It is also desirable that the gas leaving both ends of the furnace be non-flaming, but the flaming gas is only burned out near one end of the furnace. Typically, the end where the gas is burnt out is the inlet of the furnace, and the flow of gas from the heat treatment zone to the cooling zone is blocked. Devices may be provided in the cooling zone of the furnace to physically obstruct the flow of gas from the cooling zone through the furnace outlet. In order to further inhibit the flow of gas from the heat treatment zone to the cooling zone, a non-reacting gas having a horizontal velocity component in the direction of the heat treatment zone is supplied to one or more points in the cooling zone. Ru.

This makes it possible to considerably reduce the amount of gas flowing from the heat treatment zone into the part of the cooling zone opposite this zone, and thus to reduce the total amount of non-reactive gas supplied to the heat treatment zone.

These devices substantially reduce the amount of reducing gas that reaches the furnace outlet and generally eliminate the need to combust the gas at the furnace outlet. Therefore, in order to prevent air from flowing into the furnace, it is desirable to seal the flue, etc. at or near the outlet.

To create a positive flow of gas through the outlet of a horizontal furnace that prevents or substantially restricts air from entering the furnace from the outlet, the non-reacting gases have a velocity component in the direction of the outlet. It is therefore desirable to introduce the material into the horizontal furnace from one or more points at or near the outlet. Typically, such non-reactive gas also serves the function described above to reduce the proportion of non-reactive gas in the atmosphere exiting the furnace outlet. Preferably, to help prevent the ingress of air from the furnace outlet, a flow restriction device is provided to prevent the flow of gas into the furnace without preventing the metal being processed from exiting the furnace. . Typically, the device that physically obstructs the exit of gas from the cooling zone also serves to prevent gas from entering the furnace through the outlet. A suitable flow restriction device is one comprised of one or more curtains comprising a plurality of generally vertically depending fibers or filaments. When these fibers or filaments are not moved, they close off substantially the entire cross-sectional area of the furnace at or near the exit, but the metal passing through the furnace cannot be moved in any direction with its lower end. pass. The combination of such a flow restriction device and a device for introducing non-reactive gas into the furnace located at or near the flow restriction device is generally used to substantially prevent air from entering the furnace through the outlet. % effective.

In a preferred embodiment of the method of the invention, spaced partitions and/or curtains or the like define at least one chamber into which nitrogen or other non-reacting gases are introduced in the part of the cooling zone close to the furnace outlet. will be provided. The partitions are configured to allow the metal being processed to pass through several passages.

Such techniques would be commonly applied in heat treatment furnaces to reduce the overall consumption of gas.

For example, in sintering, it is known to provide a preheating zone between the sintering (or heat treatment) zone and the furnace inlet. The excavated wood etc. is oxidized in the preheating area. Accordingly, it is permissible for a limited amount of air to enter through the inlet to create an oxidizing atmosphere.The invention therefore also comprises an inlet, a heat treatment zone, a cooling zone, and an outlet provided sequentially, and at least Metals are processed in a continuous furnace with spaced partitions and/or curtains (or the like) defining at or near one end at least one chamber through which the metal to be processed passes. A method of heat treating, including introducing one or more suitable gases into the heat treatment area to create a suitable atmosphere for the heat treatment, and air from outside the furnace passing through the heat treatment areas and the heat treatment. In order to substantially prevent non-reactive gases from entering the furnace section between the zones? A method is provided that includes the steps of feeding and passing busy metal through the furnace from the inlet to the outlet.

Non-reactive gases are preferably introduced directly into the chamber.

The rate of introduction of non-reactive gas into the chamber and the physical obstruction of the partition to the gas flow are preferably such that the following conditions hold.

Pc > Pu and Pu ) Pa Here, Pc is the pressure in the chamber, Pu is the pressure of the furnace atmosphere in the vicinity of the several plans and the area between the several plans and the heat treatment area, and P& is the atmospheric pressure. .

More preferably, the horizontal furnace has at least two chambers 2511.
m is looked at and done as follows.

Pc > Pu > Pt > Pa Here, Pc is the pressure in the room closest to the heat treatment area, Pu and Pg have the same tIJK, and Pt is the pressure in the heat treatment zone; It is.

If the chamber is in the cooling zone near the outlet end of the furnace and the pressure within the chamber is greater than ambient pressure, less air will enter the cooling zone of the furnace from the furnace outlet. If the pressure in the chamber is greater than the pressure in the rest of the cooling zone and in the heat treatment zone, the formation of the required flow in the furnace by the non-flaming gas mixture leaving the furnace outlet is easily fkJ7, and at the same time The total demand for non-reactive and reducing gases can be reduced.

If two or more such chambers are used, they will typically be interconnected at substantially the same pressure.

Preferably at least two, and usually three or more, chambers are provided, each directly supplied with a non-reactive gas. In particular, in the configuration of such chambers, if necessary, a relatively high hydrogen (or other reactant gas) temperature (e.g., 50- or more (the hydrogen concentration in the outermost chamber is such that the atmosphere there becomes non-inflammatory). . Since the specific heat of hydrogen is relatively high, increasing the concentration of hydrogen in the cooling zone aids in cooling the metal. Such high hydrogen concentrations are desirable if the furnace processes particularly large amounts of metal per hour. However, in other cases this may be unnecessary and the hydrogen in the heat treatment zone may instead be introduced directly into the heat treatment zone, or by introducing most of the hydrogen into a part of the cooling zone close to the heat treatment zone. Maximum concentration is desirable.

The partition is usually hinged or pivoted to a suitable support at or near the ceiling of the furnace. If the gold 14 to be processed is an elongated strip, each partition may be in the form of a flap that seals or engages the metal to be processed and the sides of the furnace in a substantially fluid-tight manner. . If the metal to be processed is a bulkier item (e.g. a gear), each partition may be attached to the top of the furnace by a row of overlapping "finger" members on top of the furnace. It may be constructed by hanging down to the workpiece conveyance surface.

Such a configuration allows the metal being processed to pass through, but creates a physical barrier to gas flow. Various materials may be used for the partitions. For example, it can be a steel or ceramic material, or a suitable composite or laminate.

The reducing gas can be hydrogen, typically supplied from a high pressure vessel of commercially pure hydrogen, an ammonia cracker, or a hydrocarbon such as methane or propane. The reducing gas can also be a mixture of hydrogen and carbon monoxide created in situ by thermal decomposition of volatile organic compounds such as methanol. At temperatures above 700°C, 1 mole of methanol decomposes to form 1 mole of carbon monoxide and 2 moles of hydrogen. Methanol is a good source of hydrogen if the workpiece being heat treated is oily.

If there is grease on the workpiece, it may be beneficial to introduce water into the processing or preheating zone to remove the soot on the workpiece. This is after passing the non-reactive gas through the humidifier.
, may be done by placing the workpiece into a processing area.

The metal itself is not oxidized and it is therefore important that non-oxidizing and reducing conditions are maintained substantially throughout the furnace as far as the metal is concerned.

If necessary, to prevent or restrict air from entering the furnace through the inlet, it is preferred to direct the non-reacting gases with a horizontal charcoal component in the direction of the inlet between the heat treatment area and the inlet. It may be introduced into the furnace at one or more points. The inlet end of the furnace could be provided with one or more baffles or a chamber supplied with a non-reactive gas such as that used in the cooling zone. The reducing gas in the gas mixture passing through the inlet is combusted as in normal operation of a continuous heat treatment furnace.

The composition of the atmosphere in the heat treatment area of the furnace is determined, inter alia, by the type of treatment being carried out, the composition of the metal being treated, the fluid forming the atmosphere, the amount of metal to be treated entering the furnace, and the presence of ITIK oil. are selected according to their effectiveness in regulating or excluding air from the furnace.

By substantially restricting air entry into the furnace,
If necessary, the average concentration of reducing agent in the furnace atmosphere for the process consisting of is lower than in conventional furnace operation without substantially lowering the concentration of reducing gas available in the heat treatment zone. Able to perform work. Furthermore, by using commercially pure hydrogen and nitrogen rather than, for example, cracked ammonia, the dew point of the furnace atmosphere can be lowered, and thus lower reducing gas levels can be achieved than when using cracked ammonia as the reducing gas source. Able to work at level. By blocking the flow of gas from the heat treatment zone to the cooling zone, the amount of reducing gas that must be supplied to the heat treatment zone can be reduced. That is, in many cases,
The gas supply rate to a normal horizontal processing furnace can be significantly reduced.
This makes it possible to lower their operating cost (V).

Typical atmospheres that can be created in the heat treatment area for various heat treatments of different materials are shown in Tables 1 and 2 below (in some cases higher hydrogen levels may be used).

In the method of the present invention, the atmosphere in the heat treatment zone and the cooling zone of the furnace is not homogeneous. Typically, the proportion of reducing gas, such as hydrogen, contained in the atmosphere in the cooling zone is substantially lower than in the heat treatment zone. However, in some cases, a relatively high reducing gas concentration is required in a large portion of the cooling zone for efficient cooling or to increase the efficiency of the operation;
Furthermore, the reducing gas concentration may be higher than in the heat treatment zone. In such a case, the hydrogen concentration will be high. Therefore, non-homogeneous atmospheres in the heat treatment and cooling zones apply.

Alloy steel 2-4-- -Remainder mild steel -2-4-! ! I! Amarube mild steel
6-7 - Remainder mild steel/carbon tII42-4 - - -
Remaining surface mild steel/carbon steel--0,5-1--residue surface mild steel/carbon steel--15-50 remaining section 2nd Table 982---Bronze 480-680 95-5-Nickel silver 540-820 95-5
-85-- 15 Silver alloy 850-650 96- 4 -Sintered
800-120095-5-80-95-5
5-20 The method of the invention is also applicable to the heat treatment of ferrous and non-ferrous metals in continuous vertical heat treatment furnaces. An example of such a furnace is a generally vertical ascending leg having an inlet at the bottom and a generally vertical descending leg having an outlet at the bottom, the tops of the legs being interconnected. There are vertical strip annealing furnaces such as

A guiding device is usually provided in the furnace to guide the strip parts from the inlet to the outlet. A heat treatment area is provided near the top of the descending leg, and below this is a cooling area. In the operating button according to the invention in such a furnace, a non-reactive gas such as nitrogen is supplied to a plurality of spaced locations on the ascending leg and one or both of the cooling zone and the heat treatment zone of the descending leg are busy. A reducing gas, preferably containing hydrogen, is introduced.

To prevent air from entering the furnace, the preferred amount of nitrogen is 1.
One stream is introduced near the inlet of the furnace and the other stream is introduced near the outlet. If necessary, a chamber as described above may be provided on the outlet layer surface, and a similar configuration may be provided at the inlet end Mc4 (
11. In a vertical strip annealing furnace as described above, the partition would consist of a) horizontal plate with holes for guiding the IJ tube; By substantially preventing air from entering the furnace, the amount of hydrogen available to the atmosphere within the heat treatment zone can be reduced.

However, proper cooling must be provided in the cooling area. Therefore, in many such reactor systems it is preferable to maintain a relatively high concentration of hydrogen in the cooling zone due to hydrogen's relatively high thermal conductivity (compared to nitrogen). be.

Therefore, hydrogen or cracked ammonia may be introduced by the internal pressure of the cooling zone to create an atmosphere containing more hydrogen than is required in the heat treatment zone. Since hydrogen tends to rise from the cooling zone to the heat treatment zone due to its lower density compared to nitrogen or alpane, pressure may be applied to create the necessary atmosphere therein.

Nitrogen or other non-reactive gases are preferred to substantially limit or prevent the flow of hydrogen from the descending leg of the furnace to the ascending leg.
supplied to the rising leg of r. This reduces the amount of hydrogen that must be fed to the furnace compared to conventional methods.

The method of the invention will be more clearly understood from the illustrative description with reference to the accompanying drawings, in which: FIG.

This example uses a standard Birlec
A 1-pi' mesh belt furnace is concerned with annealing ferrous metal parts in a furnace.

As shown in FIG. 1, the meshbelt furnace, designated by the reference numeral 2, has an inlet 4 and an outlet 6 for the workpiece to be annealed. The furnace 2 includes a heat treatment zone 8 provided near the inlet 4.
, and a cooling zone 10 provided between the outlet 6 and the heat treatment zone 8.

The heat treatment zone 8 includes a "groover" heating element (not shown)
heated by.

The workpiece to be annealed is fed onto an endless mesh belt 11. This belt 11 is driven in an endless path extending through the furnace 2 from the inlet 4 to the outlet 6.

Belt 11 is mounted on rollers 12, and at least one of these rollers is driven by a motor (not shown). In operation, the workpiece to be annealed is placed on the belt 11 just before the inlet 4, fed through the furnace at a predetermined speed, and lifted off the belt 10 to the outlet 6.

On the underside of the belt 11 in the heat treatment zone 8 there are two inlets 14 and 16 through which gas can be supplied to the heat treatment zone 8 . These populations 14 and 16 form part of the furnace prior to being configured to carry out the method of the present invention.

Two coaxial nitrogen/methanol injectors 18 and 20 extend from the top of the furnace downward to the heat treatment area. Injector 18
is equipped with an outer pipe 22 for nitrogen and an inner pipe 26 for methanol coaxial therewith. The tip of the pipe 26 is connected to the pipe 22
placed slightly above and inside the exit. The injector 20 is substantially the same as the injector 18 and includes an outer pipe 24 for silicon and an inner pipe 28 for methanol. The injectors 18 and 20 are button-operated to cause droplets of methanol to be entrained in nitrogen, vaporized, and then impinged on the workpiece to be annealed.

A directional nitrogen injector 30 extends from the ceiling of the furnace 2 into the cooling zone 10, comprising a pipe with a puff odor or hole oriented at an angle of 45° vertically in the direction of the outlet 6. The position of the injector 30 within the cooling zone is relatively close to the furnace outlet 6. Between the injection 530 and the outlet 6, four rows of curtains 34 hang from the ceiling of the furnace 2, the lower ends of which extend a distance sufficient to pass the workpiece above the mesh belt 11. Each of these curtains typically consists of a plurality of closely fitting, generally vertically depending glass ruts that substantially block the furnace outlet when the curtain is "closed." However, as the metal passes through the furnace, it is forced open, allowing the metal to exit the furnace.

A directional nitrogen injector 32 extends downwardly into the upper portion of the cooling zone 10 with a puff formation or hole oriented at an angle of 45° to the normal to the direction of the heat treatment zone 8 . Injector 32 is located between injector 30 and heat treatment zone 8 .

In operation of furnace 2, nitrogen is typically supplied to injectors 30 and 3.
．． 2 into the cooling zone 10 to expel air from the furnace. The device for heating the heat treatment zone 8 is then activated to raise the temperature therein to the desired treatment temperature. Nitrogen and methanol are then introduced into the heat treatment zone 8 to create the required atmosphere therein. The methanol enters the treatment zone 8 in liquid form, where it evaporates due to significant expansion. Similarly, injectors 18 and 20 and inlet 14
Nitrogen introduced into the processing zone 8 from and 16 is heated from ambient temperature to the processing temperature and also expands.

The nitrogen introduced into the cooling zone 10 from the injector 32 has a velocity component in the direction of the heat treatment zone 8, and its flow is
The volume is sufficient to substantially block the flow of gases that expand and exit the heat treatment zone 8 and enter the cooling zone 10 .

Therefore, most of the gases flow in the direction of the inlet 4.

The gases enter the flue 38 where the flammable components are burned off. A sliding plate 40 is provided to regulate the gas flowing into the flue 38.

Generally, the gas flow passing under plate 40 will be sufficient to prevent significant amounts of air from entering the furnace through inlet 4. However, if necessary, nitrogen is introduced into the furnace between the processing zone 8 and the inlet 4 by a nozzle or injector (not shown) having one or more outlets directed towards the inlet 4. You may sum it up so that This additional nitrogen flow helps prevent air from entering through inlet 4.

The structure of the injector 30 and curtain 34 substantially restricts air from entering the furnace through the outlet 6.

If any flue, such as flue 38, is biased towards outlet 6 to burn off the non-flaming gases, it must be sealed to prevent air from entering the furnace through it. Must.

A nitrogen methanol supply system suitable for use in conjunction with the furnace of FIG. 1 is shown in FIG. The apparatus includes a nitrogen supply pipeline 50 connected to a commercial purity nitrogen source (not shown). The nitrogen source is typically a vacuum-insulated cypress containing liquid nitrogen, and the tank is equipped with a vaporizer to vaporize the liquid nitrogen. The supply device also includes a pipeline 52 leading to a tank (not shown) containing liquid methanol. The supply of methanol to this pipeline 52 may be effected by a pump or by the pressure of the nitrogen supply (the reduced space of the methanol tank).

An isolation or shutoff valve 54 is provided in the nitrogen pipeline 50, connecting the inlets 14 and 16 to the injector 18.20°30.32.
operated to isolate it from the nitrogen source.

A pressure regulator 56 is provided downstream of the valve 54 in the pipeline 50 to regulate the pressure of the nitrogen supplied to the pipe 58, 60, 62, 64 downstream of this which connects to the pipeline 50. Pipe 58 has two branch pipes 72 and 74
These branch pipes 72, 74 feed the injectors 30 and 32, respectively. Paizoro 0 is entrance 14
This leads to 16. Vibro 2 is connected to nitrogen pipe 22 of injector 18 and Vibro 4 is connected to nitrogen pipe 24 of injector 20. Each of the vibros 0°62 and 64 is equipped with a flow control valve 66. A flow meter 68 is provided downstream of these valves 66 . Also pipe 5
8 is also equipped with a flow meter 68. Vibro 0.62
．． A pressure regulator 10 is provided downstream of each of the 64 flowmeters 68.

Pi f5B is connected to pipe 12 and 74FCM, and flow control valves 76 and 78 are connected to these pipes 2 and 74, respectively.
will be provided. The apparatus shown in FIG. 2 includes a nitrogen humidifying device that is supplied to the injector 20. The heating device comprises a drum 82 containing water with an inlet 80 submerged under the water. Inlet 80 connects to pipeline 64 downstream of valve TO. The drum 82 has an outlet that connects with a pipe 86 that leads to the nitrogen pipe 24 of the injector 20. If the nitrogen flowing downstream of pipeline 64 and its connection with inlet 80 is to be dry, valve 84 is opened and all nitrogen in pipeline 64 passes through valve 84 to via '86. flows. When valve 84 is closed, all nitrogen in pipeline 64 passes through drum 82. The purpose of this humidifier will be explained later.

The methanol pipeline 52 is connected to a first insulating or shutoff valve 8
8. A filter 90 is provided downstream of this valve 8B to remove solids suspended in the methanol. On the downstream side of the filter 90, the pisiline 96 connects to the pipeline 52.
Connect to. Pipeline 96 connects to methanol pipe 26 of injector 18 . Pipe 96 Internal pressure flow control valve 9
8 is provided, and a flow meter 100 is installed downstream of this valve 98. A flow rate control valve 92 is provided downstream of the connection point of the pipe line 52 with the pipeline 96, and a needle 94 is provided downstream of this valve. On the downstream side of the flow meter 94, the pipeline 52 connects to the methanol pipe 28 of the injector 20.
Connect to.

Modifications are made to install injectors 18, 20, 30, 32 and curtain 34, and inlets 14 and 16 are connected to a nitrogen source (and any flue at the exit end of the furnace is closed). 2.000 per hour.
It was operated by supplying standard cubic feet (54 air 3) of concentrated exothermic gas to heat treatment zone 8 through inlets 14 and 16. The resulting flaming gas mixture was burnt out at both ends of the furnace. It has been found that when the furnace is modified as shown in FIGS. 1 and 2, bright workpieces can be obtained by carrying out the method of the invention. 1
In one typical example, a universal joint forging is annealed at 900°C in heat treatment zone 8 and then cooled in cooling zone 10.
It was cooled inside to almost the outside temperature. The supply of nitrogen and methanol to each fluid inlet and injector was performed as follows.

Inlets 14 and 16: 220 standard cubic feet per hour (5,9
4Fjl') nitrogen.

Injectors 18 and 20: 440 cubic feet per hour) (1
1,8811') of nitrogen and 2 liters of methanol per hour.

Injector 30: 100 standard cubic feet per hour (2.7 m3
) of nitrogen.

Injector 32: 100 standard cubic feet per hour) (2,7,
3) Nitrogen.

The flow was split equally between injectors 18 and 20. One liter of methanol per hour decomposes at the processing temperature to produce 20 standard cubic feet per hour (0.54 ms) of -carbon oxide and 40 standard cubic feet per hour (1.08 Fm') of hydrogen. Therefore, the total flow rate of gas into the furnace is 1.0% per hour.
000 standard cubic feet (27 m'), which is found to be half the exothermic gas flow rate.

Various parts, from large castings to small presses, are processed in a furnace supplied with nitrogen and methanol at the above rates and with a maximum temperature in the heat treatment area in the range of 720 to 1060°C. I was disappointed.

FIG. 3 shows the changes in the composition of the furnace atmosphere at various points in the furnace when the processing zone 8 is operated at 970°C. As can be seen in this figure, the concentration of hydrogen in the atmosphere in the treatment zone 8 is about 7 g, and from there it gradually decreases along the cooling zone 10 in the direction of the outlet 6 and reaches the outlet 6. Before that, it had fallen to less than 1%. Similarly, carbon monoxide levels fall from values between 3.5% and 496 in the heat treatment zone 8 to values of less than 1 Ls at the end of the cooling zone 10 opposite the heat treatment zone 8. Similarly, the carbon dioxide concentration decreases from about 0.496 in the heat treatment zone 8 to less than 0.1% at the end of the cooling zone 10 opposite the heat treatment zone 8 (all percentages are in terms of volume). Afu). That is, the gas leaving the furnace outlet 6 is substantially free of flammable reducing gas.

In this example, methanol was chosen as the reducing gas source since the workpiece being treated was oily. This provides a relatively high dew point of the atmosphere within the heat treatment zone and eliminates entrained oil buildup on the heating element when a nitrogen methane or nitrogen hydrogen atmosphere is used.

However, since the cooling zone 10 is supplied with nitrogen, a predominantly non-reactive atmosphere is created there, so that workpieces with a bright finish can be obtained.

Injectors 18 and 20 were designed such that their pipes 22 and 24 were closed at the bottom but provided with orifices on their sides. The methanol exiting pipes 26 and 28 then hits the closed ends of pipes 22 and 24.
It breaks down into drops.

These droplets are carried by nitrogen through the orifices of pipes 22 and 24 and into the treatment zone 8. This prevented the relatively fast moving methanol jet from striking heating elements in other parts of the furnace before it vaporized. If such a blow were to occur, it would result in carbon deposits on the workpiece.

Also, at the levels of hydrogen and carbon monoxide used in heat treatment zone 8, the ingress of air into the furnace is sufficient to reduce the dew point of the atmosphere in cooling zone 1o to such a level that inferior quality workpieces are produced. It has been found that it is generally desirable to direct the nitrogen from the injector 3o toward the curtain 34 so as not to increase the temperature.

A heating ram 82 was used to prevent soot from adhering to the furnace structure above the workpiece by adding water vapor to the atmosphere, especially if the workpiece had oil or grease on it.

When processing large presses, a flame curtain was created under the mesh belt 11 at the inlet end of the furnace. The purpose of this is to consume the oxygen in the air trapped on the underside of the press.

EXAMPLE 2 This example concerns the sintering of bronze onto a steel backing in a suitable continuous sintering furnace as shown in FIG.

In FIG. 4, a continuous furnace 200 includes an inlet 202 for the workpiece to be sintered, a heat treatment zone 204 having a device (not shown) for heating the workpiece to a processing temperature, an inlet 202 and a heat treatment zone 202.
4, a workpiece outlet 20B, and a cooling zone 210 between the heat treatment zone 204 and the outlet 208. Adjacent to the heat treatment zone 204 of the cooling zone 210 is an injector pyso 212 that supplies a suitable gas mixture into the heat treatment zone 204 to create the required atmosphere within the heat treatment zone 204 . Inlet 212 is part of the normal fittings of the furnace. In addition to the inlet 212, eight injectors 214 are connected to the cooling zone 210.
extends inward. Each injector 214 is provided with a respective nitrogen supply pipeline 216 and a flow control valve 218 and a calibrated orifice 220 downstream thereof.

All pipes 216 are 2-in 222 common pipes for nitrogen supply.
Connect to.

A nitrogen distribution pipe 224 extends into the furnace near outlet 208. The orientation of this distribution pipe 224 can be adjusted to change the direction of gas emitted therefrom.

The orientation is preferably such that a substantial external velocity component is created in the direction of the exit. Normally, distribution pipe 22
4 has an exit orifice whose axis lies at an angle of 45° to the vertical.

A curtain 226 between the injection pipe 224 and the outlet 208
will be installed. The construction of this curtain is the same as that described in FIG.

Distribution pipe 224 has its own nitrogen supply pipe 228 which is equipped with a flow control valve 230 and a calibrated orifice 232 downstream thereof. Pipe 228 is connected to pipeline 222.

The cooling zone 210 is typically cooled by a water jacket 234.

By means of a distribution pipe 238 similar to distribution pipe 224,
Sections 20& of the furnace 200 are also supplied with nitrogen. pipe 2
38 is installed so that a substantial velocity component of the gas to be injected from it is in the direction of the inlet 202. Typically, the pipe 238 is constructed so that the gas exiting from it is at a 45° angle to the vertical. pipe 238
is connected to pipe 240. This pi f240 includes a certified orifice 242 and a flow control valve 24 upstream of the orifice 242.
4.

The gas inlet 212 is connected to a gas mixing panel 246, which in turn is connected to a nitrogen source (not shown) and a source of cracked ammonia. A gas-filled Ropaiso 250 is provided as a standard fitting at the inlet and outlet ends of the furnace. These pipes are sealed. Flues 252 are also provided at the inlet and outlet ends of the furnace. The outlet end Q flue of the furnace is sealed.

The operation of the furnace of FIG. 4 is substantially the same as that of FIG. The workpiece to be sintered is conveyed through furnace 200 by suitable equipment (not shown). A selected mixture of nitrogen and decomposed ammonia is supplied to the inlet 21 located within the cooling zone 210.
2 into the heat treatment zone 204 of the furnace. Injector 2
14 introduces nitrogen at a plurality of spaced locations within the cooling zone 210, thereby providing a cooling nitrogen stream that helps prevent free flow of gas from the inlet 212 and heat treatment zone 204 toward the outlet 208. created within area 210. Further, curtain 226 prevents gas from exiting furnace 200 through outlet 208. curtain 22
6 also prevents air from entering the furnace through the outlet 208 along with the nitrogen injected from the distribution pipe 224 towards the curtain. Similarly, nitrogen directed from the distribution pipe 238 toward the inlet 202 helps prevent air from entering the furnace through the population 202.

The nitrogen and cracked ammonia entering heat treatment zone 204 expand and exit heat treatment zone 204 through zone 206 and into flue 252 for introduction of nitrogen from injector 214 into cooling zone 210 . In this flue, the flaming gas (hydrogen) contained in the ζ is burned out. The introduction of nitrogen into cooling zone 210 from injector 214 and distribution pipe 224 ensures that a negligible amount of flaming gas is contained in the gas exiting the furnace through outlet 208. Become something.

Typically, when sintering powdered bronze to a steel backing, an atmosphere containing 20 to 30 volumes of hydrogen and the balance nitrogen is preferably used. This atmosphere is supplied into the furnace through inlet 212 and sealed inlet 250. The amount of hydrogen required can be substantially reduced, and each injector 214 and distribution pipe 2
The nitrogen flow rate to 24 is typically 400 to 50 ml per hour.
0 standard cubic fee) (from 10.8 to 13.5 m3).

This nitrogen flow is divided evenly between the eight injectors and distribution pipes.

The gas mixture supplied to pipe 212 and thus to heat treatment zone 204 typically expands at a rate of 50 standard cubic feet per hour (50 standard cubic feet per hour).
1,35 m3) of decomposed ammonia (25 m3 of nitrogen and 75 m3) of decomposed ammonia
- hydrogen) and 300 standard cubic feet per hour) (8,1 m
') Let the following be a mixture of nitrogen. Nitrogen is preferably Hiro,
150 to 2001 per hour! quasi-cubic fee) (4,05
5.4 m') to the distribution pipe 238.

Example 5 This example concerns bright annealing of stainless steel strip performed in a vertical annealing furnace.

In FIG. 5, a vertical stainless steel bright annealing furnace 300 includes an ascending leg 302 and a descending leg 304 connected at the top by a connecting section 306.

There is a strip inlet 308 at the bottom of the rising leg 302 and a strip outlet 310 at the bottom of the descending leg 304. The inlet 308 and outlet 310 are narrowed compared to the overall cross-sectional area of the leg. Baffle 3 near entrance 3080
12 is provided, and an inlet 3 is provided from above the baffle.
Regulates the flow of gas toward 08. A similar baffle is provided near outlet 3100 to restrict gas flow from above to outlet 310. A guide roll 314 is provided at the inlet 3 for feeding the strip continuously through the furnace.
08, exit 310 and section 306.

A heat treatment zone 320 is set in the upper section of the descending leg 304. This heat treatment area is surrounded by radiant heating elements 322 from the outside of the lower leg 304. A cooling zone 318 is provided below the heat treatment zone 320 in the lowering leg 304 . The cooling zone 318 includes a fan (not shown) to circulate gas therein.

Gas inlets to the ascending leg 302 and descending leg 304 of the furnace 300 are provided at multiple spaced locations on the legs. The first nitrogen population 324 is the area near the entrance 308 of the ascending leg (population 3
08 and its baffle 312) to prevent air from entering the furnace 300.

A plurality of inlets 326, all connected to the riser legs of the furnace, create an atmosphere within the riser legs consisting essentially of nitrogen. A sixth population 328 supplies nitrogen to the portion of the descending leg 304 near the outlet 310 and between the outlet and its baffle 312 . The nitrogen thus directed to the outlet 310 substantially completely prevents air from entering the furnace through the outlet 310. A plurality of inlets 330 supply hydrogen or cracked ammonia (3 parts hydrogen and 1 part nitrogen) to the cooling zone 318-%
supply Nitrogen and hydrogen (or cracked ammonia) to the furnace
The relative feed rates of are selected to create favorable conditions in the cooling zone and heat treatment zone for bright annealing of the stainless steel. By eliminating all or almost all air from the furnace, the amount of hydrogen or cracked ammonia that can otherwise be used can be much lower. Furthermore,
By sending a sufficient amount of nitrogen to the ascending leg 302 to prevent the flow of hydrogen from the descending leg 304 to the ascending leg 302.
The rate of hydrogen feed to the furnace can be limited to only that necessary to create a suitable atmosphere in the cooling and heat treatment zones. Therefore, much less hydrogen can be present in the atmosphere than in conventional processes using cracked ammonia. Nitrogen also flows from the ascending leg 302 to the descending leg 304.

The atmosphere within cooling zone 318 and heat treatment zone 320 therefore includes both nitrogen and hydrogen. However, the proportion of hydrogen in the cooling area is higher.

Typically, in conventional bright annealing of stainless steel in a furnace using decomposed ammonia, 2.600 cubic feet per hour (70,2 m3) of decomposed ammonia were used; 1,70 per hour
0 to 1,800 cubic feet (45.9 to 48.6
m3).

Proper cooling within the cooling zone 318 typically involves the use of an atmosphere containing a higher concentration of hydrogen in the heat treatment zone. This is because hydrogen has higher thermal conductivity than nitrogen.

If the hydrogen source is cracked ammonia, the hydrogen concentration in the cooling zone will be 60 to 62 degrees (50°C dew point).

Also, if the hydrogen source is a cylinder of commercially pure hydrogen, the hydrogen concentration should be 54-60% by volume (55°C dew point). However, the hydrogen concentration in the atmosphere in the heat treatment zone is typically between 56 and 43 vol. h when the hydrogen source is cracked ammonia, and between 28 and 41 vol. h when the hydrogen source is a cylinder of compressed commercially pure hydrogen. Good morning. This kind of atmosphere is
Nitrogen is introduced into the lift leg 302 from inlets 324 and 326 at a flow rate within the range of 800 to 1.000 cubic feet (21.6 to 27 m3) per hour (300 to 400 cubic feet per hour) (8.1 to 27 m3). Inlet 3 at a flow rate of 8 mB)
28 into the descending leg 304 and cracked ammonia (or 200 to 300 cubic feet per hour) into the cooling zone 318 from the inlet 330 at a flow rate of 400 to 450 cubic feet per hour (or 200 to 300 cubic feet per hour). fee)
It can be made by introducing (hydrogen) at a flow rate of 5.4 to 8.1 vus. The less dense hydrogen moves upward, and the nitrogen in the ascending leg 302 moves to the descending leg 304.
As a result, the gas analysis results are typically 5'Jk as shown in Table 3.

The results of this analysis are based on a quantitative stainless steel strip (30
0 series) was annealed at a temperature of 1050'0. The exact amount of hydrogen required within the cooling zone will depend on the thickness of the strip. Generally, the thicker the strip, the more hydrogen is required within the cooling zone. If necessary, the furnace can be shut down periodically, for example on weekends, but the gas mixture of 96 volumes of nitrogen and 4 volumes of hydrogen can still be removed from section 306.
By supplying the same atmosphere throughout the furnace, the conditions that create such an atmosphere are maintained.

Example 4 This example concerns the bright annealing of ferrous or non-ferrous metals in FHD PP'3.

In FIG. 6, a mesh belt (not shown) is being processed.IJ pieces and other metals are fed into the furnace through an inlet 602 and out of the furnace through an outlet 604. The furnace includes, sequentially from inlet 602 to outlet 604, an inlet zone 606, a heat treatment zone 608, and a cooling zone 610. 610 in the cooling zone opposite the heat treatment zone 608
At the ends of the chambers 612, 614, 616 are provided which are defined by generally vertical partitions 618 and the walls of the furnace. A sliding plate 619 is provided at the outlet 604.

This sliding plate co-locates with the partition 618 closest to it and defines yet another chamber 621''4!:.

A flare-off device 620 is coupled to the top or ceiling of the inlet area 606 at a location within the inlet area 606 between the chamber 622 and the heat treatment area 608 . The chamber @ 22 includes a wall of the furnace, a first sliding plate 626 provided at an angle to the vertical at the inlet 6020, and a hinged plate 6.
24. Since the hinged plate 624 can be moved up and down, its lower edge and mesh belt (
(not shown) can vary.

Chambers 612, 614, and 616 communicate with upper nitrogen supply fill chamber 628 and upper nitrogen supply fill chamber 630, respectively, and chamber 622 also communicates with upper and lower similar nitrogen supply fill chambers 632.
, 634.

The furnace also includes a variable angle nitrogen injector 636 in the inlet area 606 of the furnace between plate 626 and heat treatment area 60B. A nitrogen population 640 is also provided in the cooling zone 6100 adjacent to the heat treatment zone 608. Additionally, a variable angle hydrogen injector 638 is provided in cooling zone 610 adjacent chamber 612 .

The configuration of chambers 612, 614, 616 is shown schematically in FIG.

As can be seen, the partition 618 is constructed by a steel plate or flap hinged to a support 642 depending from the ceiling 644 of the furnace.

A plurality of spaced apart slots 648 are provided in the ceiling 644 and floor 646 of the furnace. Nitrogen passes through chamber 6
28 and 630 to chambers 612, 614, and 616. Chambers 628, 630 are provided with baffle plates 654 and 656 in the 0 chamber 628, 630 having nitrogen ports 650 and 652 connected to the nitrogen source and connected to the inlet 65.
0.652 and slot 648 to prevent a direct path. Therefore, during operation, nitrogen is supplied to the baffle 654°6.
56 detour, slot) 648Y path, typically creating a laminar flow of gas into the furnace. In order to deflect the nitrogen in the direction of the outlet and create a horizontal velocity component in that direction, the partition 618 is angled at an angle of approximately 10'' with respect to the vertical MIC such that its lower edge is closer to the outlet 604 than its upper portion. It can be hung by holding it.

The lower edge of each partition 618 contacts the metal strip being processed as it passes through the furnace. If necessary, sealing means (not shown) may be provided at the edges of each partition 618 to substantially eliminate gas Rk between the partition and the P-wall. However, between the rooms,
Communication remains between what passes over the upper edge of the partition and what passes through the mesh belt 658 of the furnace. However, it is easy to provide a seal at such an upper edge if necessary. In general, the less communication between chambers 612, 614, and 616, the less hydrogen and other gases can exit the furnace through the outlet end 604, and the more air can enter the furnace through the outlet end 604. Therefore, the chamber 61
2,614,616 and the heat treatment zone 608 to create a high hydrogen concentration in the cooling zone 610? This also creates a non-flaming atmosphere in the chamber 621 next to the outlet 604 and substantially prevents air from entering the furnace through the outlet 604.

The operation of the furnace shown in FIGS. 6 and 7 is carried out as follows: Phonemes are supplied to chambers 628.630.632.634,
Expel the air from the furnace. A heating device (not shown) K provided in the furnace heats the heat treatment area 608 to the heat treatment temperature. Hydrogen is then supplied to the furnace from variable angle injector 638. The angle of the injector 638 is typically such that it directs the gas downwardly at a 20° angle to the vertical and has a horizontal velocity component in the direction of the inlet end of the furnace. The hydrogen reacts with residual air in the heat treatment zone, and once substantially all residual air is removed, the strip is continuously passed into a furnace to be annealed. When this process is carried out, the furnace is set so that inlets 636 and 640 are closed and plates 624, 626, 619 are in the lowest position.

Nitrogen is supplied to chambers 612 and 61 from upper and lower supply chambers 628 and 630.
4. Sent to 616. These chambers 612, 614, 61
6, a pressure higher than the outside air pressure is applied. A portion of the nitrogen therefore flows from the chamber 616 to the chamber 621 and exits the furnace through the outlet 604. Injector 638 to cooling zone 610
Hydrogen is introduced into the chambers 616, 614, 612.
The flow of nitrogen into the cooling zone 610 causes a gas mixture of nitrogen and hydrogen to flow into the heat treatment zone 608 . This directional flow is caused in part by the obstruction to reverse flow provided by partition 618 and the gas pressure in chambers 612, 614, 616, and in part by the flaming gas exiting heat treatment zone 608. 7 rare off device 620
(such combustion helps direct the flow towards the furnace inlet 602).

As the gas flows toward the heat treatment zone 608, casing or diffusing, it becomes progressively heated by convection from the heat treatment zone. Is this kind of heating gas'? :j1
and create a back pressure in the cooling zone 610. Thus, as long as nitrogen is supplied to chambers 62B and 630 at a suitable flow rate, the pressure in cooling zone 610 adjacent to chamber 612 and located between this chamber and heat treatment zone 608 will be the ambient pressure. and higher than the pressure within the heat treatment zone 608 itself.

A portion of the hydrogen flows into chamber 6 in a direction opposite to the overall direction of flow.
12,614.61f1. The nitrogen and hydrogen introduction rates are set such that the hydrogen concentration in the cooling zone 610 and heat treatment zone 608 of the furnace is relatively high.
(e.g., 50 volumes or more), the hydrogen that diffuses through the chambers 612, 614, and 616 generally in the direction of the outlet 604 is gradually diluted by the nitrogen, so that the furnace The gas mixture as it exits the outlet 604 will be non-flammable.

A portion of the gas in the heat treatment zone 608 diffuses into the cooling zone 610, but because of the pressure differential in the direction of the net flow of gas through the furnace, the majority of the gas in the heat treatment zone 608 diffuses into the furnace inlet 602. The flaming gas mixture flowing in the direction is combusted in the flare-off device 620 as described above. Supply room 6
Nitrogen supplied to chamber 622 from 32 and 634 prevents hydrogen from flowing beyond the combustion zone, and air is supplied to chamber 622 from inlet 60.
This helps prevent water from flowing into the furnace through the two pipes.

By keeping the rate of air ingress into the furnace low in this manner, the amount of reducing gas needed to create a non-oxidizing atmosphere can be much reduced. Furthermore, by creating only one flow at one flare-off or combustion outlet, the total amount of gas used in the furnace per unit time can be reduced. These advantages of the invention are due to the quality of the treatment on the metal or workpiece! : You can get it without dropping it.

Table 4 summarizes the experimental results obtained when the heat treatment zone was operated at a temperature of 600°C. The concentration of hydrogen is measured by taking samples at various locations in the furnace from location A to the workshop, and these samples are used to measure the oxygen potential of the atmosphere from location A to the workshop.
was used.

The distance from location A to the construction site is as follows.

A- in chamber 622; B- in inlet area 606 closer to flare-off device 620; C- in heat treatment area 608; D- in heat treatment area 608 closer to cooling area 610 than location C.
E-cooling zone 61 between heat treatment zone 608 and chamber 612;
0, G-chamber 614, H-chamber 616, Knee-chamber 621, C. Experiments 1 and 2 allow the hydrogen concentration in the cooling zone and heat treatment zone to be relatively high, and the This indicates that the gas leaving the furnace is non-flammable. In run number 6, additional nitrogen was supplied to the furnace through inlet 640. As a result, the proportion of hydrogen in the heat treatment zone was substantially lower than in the first and second experiments, although the proportion of hydrogen in the cooling zone was still relatively high. This indicates that a totally unidirectional flow from the cooling zone to the heat treatment zone was obtained.

Experiments four and five show that all of the nitrogen supplied to chambers 612, 614, 616 can be introduced from upper fill chamber 628, and the nitrogen supplied to chamber 622 can be introduced from lower fill chamber 634.

A chamber near the outlet end of the furnace can be made by a custom-made unit attached to the outlet end, thereby extending the length of the furnace.

The method of the invention can be carried out in a continuous sintering furnace having a zone where the oil and lubricant applied onto the workpiece to be sintered is oxidized. Such a zone is located between the furnace inlet and the heat treatment zone. Typically the sintering temperature in the heat treatment zone is 1
100℃ and the lubricant removal zone from 500 to 700℃
The temperature is maintained within the range of . The furnace may be equipped with a chamber at its inlet and outlet ends K, as shown in FIGS. 6 and 7. In such a furnace, gas is supplied at the following rate and a suitable gas flow is created by burning off the gas only near the inlet end. Nitrogen is supplied to the chamber at the end of the cooling zone opposite the heat treatment zone at a rate of 150 to 200 cubic feet per hour (4.05 to 5.41 m3), and to the chamber at the inlet end of the furnace at a similar rate. Supplied by Gas generated from an endothermic generator (typically containing about 40 volumes of hydrogen) at a rate of 100 cubic feet (2,7-1') per hour is outside the chamber within the cooling zone, but not within the cooling zone. Flows into the cooling area at a nearby point. Such an endothermic gas also produces 250 cubic feet per hour) (6
,75,3) into the cooling zone near the heat treatment zone, and nitrogen is introduced into the cooling zone at a rate of 650 to 400 cubic feet per hour (9,45 to 10.8 F3) per hour. will be introduced to This creates a flow of nitrogen and hydrogen generally in the direction of the heat treatment zone to maintain reducing conditions in both the cooling zone and the heat treatment zone. Two hundred cubic feet (5,4113) humidified nitrogen per hour is pumped into the area between the heat treatment zone and the oxidation zone of the furnace to create conditions for oxidation of oils, lubricants, etc. in the oxidation zone. It will be done. This humidified nitrogen addition is carried out to oxidize lubricants, etc. on the sintered workpiece without decarburizing the workpiece itself. The flaming gas mixture exiting the oxidation zone is burnt out. This step helps create a gas flow generally in the direction of the furnace inlet.

The gas demand is substantially less than in conventional furnace operation where the flaming gas mixture is burnt out at both the inlet and outlet ends.

[Brief explanation of the drawing]

1 is a schematic representation of a Metschbelt furnace for carrying out the process of the invention; FIG. 2 is a schematic diagram of a flow circuit for supplying nitrogen and methanol to the furnace of FIG. 1; FIG. , a graph showing typical examples of the composition of the atmosphere at various points along the length of the furnace; Figure 4 is a schematic diagram of a continuous sintering furnace; Figure 5 is a graph showing a typical example of the composition of the atmosphere at various points along the length of the furnace; FIG. 6 is a schematic diagram of another Metschbelt furnace for carrying out the method of the invention; FIG. 7 is the structure of the chamber forming part of the cooling zone of the furnace of FIG. This is a schematic diagram showing the diagram. 2...Mesh belt heat treatment furnace, 4...Workpiece inlet, 6...Same outlet, 8...Heat treatment zone, 10...Cooling zone, 11...Mesh belt, 12...Belt feeding Roller, 14.16... Gas supply inlet, 18.
20... Nitrogen/methanol injector, 30.32...
Nitrogen injector, 34... Curtain, 38... Flue, 4
0... finger plate, 50... nitrogen supply pipeline, 52... methanol supply pipeline, 82...
- Humidifier, 200... Continuous sintering furnace, 202... Workpiece inlet, 204... Heat treatment area, 206... Inlet area, 208... Workpiece outlet, 210... Cooling area ,
212... Gas mixture inlet vibrator, 214... Nitrogen supply injector, 216. 228... Nitrogen supply pipeline, 222... Nitrogen supply common pipeline, 224.
238...Nitrogen distribution pipe, 226...Curtain,
234... water jacket), 246... gas mixing panel, 252... flue, 300... vertical annealing furnace, 302... rising leg, 304
... Descending leg, 306 ... Connection section, 308.
... Workpiece inlet, 310 ... Same exit, 312 ... Baffle, 314 ... Workpiece guide roll, 318 ...
Cooling zone, 320... Heat treatment zone, 322... Heating element, 324° 326.328... Nitrogen inlet, 33
0...Hydrogen or ammonia inlet, 602...FHD mesh belt heat treatment furnace workpiece inlet, 604...Same outlet, 606...Inlet area, 608
...Heat treatment zone, 610...Cooling zone, 612,6
14゜616.621,622... room, 618...
Partition, 619.624,626...Plate, 62
0...Flare off device, 628, 630, 632, 6
34... Phoneme supply filling chamber, 636... Nitrogen injector,
638...Hydrogen injector, 640...Nitrogen inlet, 64
2... Partition support, 644... Furnace ceiling, 646...
- Same method, 61...Slot, 650,652...Nitrogen inlet, 65~. 656... Baffle, 658... Metschbelt. Agents Asamura and Kogai 4 engravings of the drawings (no changes to the content) Board procedure amendment (method) Nozuki e day, 1948 Mr. Commissioner of the Japan Patent Office 1, Indication of the case 1978 Patent application No. ΔRρtry', = 2. Name of the invention: 1.3. Relationship with the supplementary iTE case: Address of patent applicant: 4. Agent: 5. Date of amendment order: 1933? Year/Month 2C Day 6, Number of inventions increased by amendment 7, Subject of amendment

Claims (1)

[Claims] (1) A method of heat treating metal in a continuous furnace having sequentially provided inlets, heat treatment zones, cooling zones, and outlets, wherein air enters the furnace through the inlets and outlets. introducing non-reacting gases and reducing gases into predetermined locations within the furnace; substantially preventing the entire furnace from undergoing non-oxidizing or reducing conditions; In order to create atmospheres with different compositions, VC, f
A method comprising the steps of creating a gas stream and passing the metal through the furnace from the inlet to the outlet. (2. The method of claim 1, wherein the continuous furnace is a horizontal furnace, and the gas exiting the heat treatment zone substantially flows from the outlet toward the inlet. (3) The method of claim 1 or 2, wherein the non-reacting gas is removed from one of the cooling zones to prevent gases from the heat treatment zone from escaping through the cooling zone.
A method of supply to one or more locations. (4) In the method of claim 6, the non-reacting gas and reducing gas are introduced into the cooling zone and a flow is created such that a substantial portion of the reducing gas flows into the heat treatment zone. How to be done. (51%) In the method of any one of claims 2 to 4, the gas passing through the outlet prevents or substantially restricts air from entering the furnace through the outlet. A method in which the non-reacting gas is introduced into the furnace from one or more points within the cooling zone or near the outlet to create a positive flow of The method of any one of paragraphs 2 through 5, wherein the outlet is provided with a flow restriction device that prevents gas flow into the furnace without blocking the metal to be processed from exiting the furnace. (7) The method according to any one of claims 2 to 6, wherein a portion of the cooling zone near the furnace outlet:
spaced partitions and/or curtains (or the like) defining at least one chamber through which the metal to be treated is passed, the non-reacting gas being introduced directly into at least one of the options; method. (8) defining, at or near at least one end, at least one chamber through which the metal to be treated can pass, comprising a sequential inlet, a heat treatment zone, a cooling zone, and an outlet; A method of heat treating metal in a continuous furnace comprising spaced partitions and/or curtains (or the like), in which one or more suitable heat treatment areas are provided to create a suitable atmosphere for the heat treatment. Introducing gas, introducing a non-reactive gas into the passages to substantially prevent air from outside the passages from entering through the passages and into the furnace section between the passages and the heat treatment area. A method comprising the steps of feeding and passing the metal through the furnace from the inlet to the outlet. (9) In the method of claim 7 or 8, Pc ) Pu and Pu ) Pa, where P
c is the pressure in the plan or one of the chambers, Pu is the pressure in the cooling zone near the chamber and between the plan and the heat treatment zone, and Pa is the ambient pressure. (II % In the method of claim 9, at least two chambers are provided, and Pc > Pu > Pt > Pa, where:
A method, wherein Pc is the pressure in the chamber closest to the heat treatment zone, Pu and pa are the same as in claim 10, and pt is the pressure in the heat treatment zone. all The method of claim 1, wherein the furnace is a vertical furnace having two generally vertical legs connected at the top, and the workpiece to be heat treated is in one of the legs (the rising leg). a heat treatment zone is provided in or near the top of the descending membrane, and a cooling zone is provided in the descending arm. Method provided on the lower side of. α2, during the method of claim 11, reducing gas is introduced into the cooling zone and/or heat treatment zone, substantially inhibiting the flow of the reducing gas into the ascending leg. A non-reactive gas is introduced into a plurality of locations in the ascending leg to prevent overloading, and a non-reactive gas is introduced into both the ascending leg and the descending arm to substantially prevent air from entering the furnace. the reducing gas is hydrogen and is introduced into the cooling zone, the cooling zone and the heat treatment zone containing an atmosphere containing nitrogen and hydrogen; the proportion of hydrogen in the heat treatment zone atmosphere is greater.